Abstract

Background: Given the anatomical proximity, pathologic conditions and endodontic treatment procedures in maxillary posterior teeth may affect the maxillary sinus.

Case description: This report describes a case of large extrusion of filling material to the maxillary sinus, resulting in persistent acute pain and requiring hospitalization and surgical removal of the material via videolaparoscopy. A 34-year-old female experienced persistent pain in the left upper posterior region of the face, three months after endodontic treatment of tooth 14. Radiographs revealed a large amount of filling material in the maxillary sinus. Despite using analgesics, the pain persisted, with an additional burning sensation in the infraorbital area. The endodontist who treated tooth 14 confirmed that the filling was completed using Tagger’s Hybrid technique with gutta-percha and AH Plus sealer. A cone-beam computed tomography (CBCT) was requested, revealing a missed MB2 canal in tooth 14. Non-surgical endodontic retreatment ameliorated the pain; however, symptoms persisted, necessitating the surgical removal of the extruded material, which was performed via videolaparoscopy. Six months later, the patient was asymptomatic regarding tooth 14, but tooth 13 was extracted and replaced with an implant that later perforated the sinus floor. After implant replacement, the patient's pain was completely resolved.

Conclusions: This case highlights the need for caution when performing endodontic treatment on posterior maxillary teeth due to their proximity to the maxillary sinus. In cases where root apices contact, invade, or are close to the sinus, thermoplasticized root canal obturation techniques should be avoided because of the increased risk of extrusion complications and consequences. CBCT imaging significantly improves diagnostic accuracy in cases with persistent symptoms and is an important tool in treatment planning.

Introduction

The success of endodontic therapy depends on the proper cleaning, shaping, and filling of root canals, as well as effective coronal seal (Siqueira 2001, Siqueira et al. 2005). During treatment, filling materials, irrigants, debris, and microrganisms can be extruded into the periradicular tissues (Alves et al. 2018, Azizi Mazreah et al. 2022, Monteiro et al. 2024). Although small amounts of extruded material may not impact treatment prognosis, significant extrusion of filling material can have severe consequences, particularly if the material reaches critical anatomical structures such as nerves, blood vessels, or the maxillary sinus (Yamaguchi et al. 2007, Alves et al. 2014, Ricucci et al. 2016). These complications include inflammation, pain, infection spread, extraradicular infection, paresthesia, or even treatment failure (Signoretti et al. 2011, Arias et al. 2013, Alves et al. 2020, Pereira et al. 2022). Therefore, the filling material should be confined within the root canal, ideally positioned from 0.5 to 2 mm short of the root apex (Sjogren et al. 1990, Siqueira et al. 2005).

Achieving a hermetic seal is the primary goal of root canal obturation, and gutta-percha remains the material of choice. Most obturation techniques involve plasticizing and compacting gutta-percha to achieve this seal. However, the heat and the forces applied during condensation increase the flowability of the filling mass, contributing to apical extrusion (Swathika et al. 2024). In addition, the anatomical proximity of the root apices of upper molars to the maxillary sinus raises the risk of unintentional extrusion into the sinus, which may result in maxillary sinusitis (Ok et al. 2014, Tian et al. 2016).

This article describes a case of large extrusion of filling material during the root canal treatment of a molar into the maxillary sinus, resulting in persistent acute pain and requiring hospitalization and surgical removal of the material via videolaparoscopy.

Case report

A 34-year-old female patient was referred by a general dentist for evaluation of persistent intense pain in the left upper posterior region of the face, that started three months after endodontic treatment of tooth 14. A periapical radiograph provided by her dentist revealed a large radiopacity, suggestive of extruded filling material at the palatal root of tooth 14, extending through the cortical bone into the left maxillary sinus (Figure 1A). The patient reported severe pain during the filling procedure and was informed that the symptoms would resolve shortly. Despite taking analgesics and anti-inflammatory medications, which provided some relief, the pain persisted, and she was only able to chew unilaterally. Additionally, she experienced a burning sensation in the infraorbital region.

The patient also reported root canal treatment of tooth 13 ten years ago and attributed her current pain to tooth 13, believing tooth 14 had been treated mistakenly. However, her endodontist was contacted and according to him, tooth 13 tested negative for all periapical tests, while tooth 14 was identified as the source of pain. The endodontist also informed that the root canal treatment of tooth 14 was completed in a single visit, using thermoplasticized gutta-percha and AH Plus sealer with Tagger’s Hybrid technique.

Clinical examination revealed no fistula, swelling, or mucosal changes, though tenderness was noted upon palpation and percussion. Periodontal examination showed no pocket depths or bone loss. A new periapical radiograph revealed that much of the extruded material had been reabsorbed. However, due to the patient’s concerns about tooth 13 and the persistent symptoms, a vertical root fracture in tooth 13 or a missed MB2 canal in tooth 14 was suspected (Figure 1B). Therefore, a Cone-Beam Computed Tomography (CBCT) scan was requested to investigate further.

The CBCT scan confirmed the extravasation of endodontic filling material from the palatal root of tooth 14 into the left maxillary sinus and allowed the identification of a missed MB2 canal in tooth 14 while ruling out a fracture in tooth 13. Additionally, a hyper-dense image compatible with a foreign body was noted at the interface of the anterior ethmoid cells in the left maxillary sinus (Figure 1C).

In this context, endodontic retreatment of tooth 14, including the MB2 canal, was indicated and completed in two visits, with calcium hydroxide used as intracanal medication between sessions.

Following the retreatment, the patient became asymptomatic concerning tooth 14, and the final restoration was completed. However, symptoms in the infraorbital area persisted, likely due to the foreign body in the sinus. Therefore, the patient was referred to an otolaryngologist, and surgical removal of the material via videolaparoscopy, performed in a hospital due to the complex anatomy and limited access to the area. The removed material, a compact hardened mass, was sent for histological analysis (Figure 2A).

At the six-month follow-up, the histological report described the material as a dense filling substance (gutta-percha and sealer) with irregular edges, osseous fragments, and measuring 8 mm at its longest extension. During this period, tooth 14 remained asymptomatic. A periapical radiograph showed minimal overfilling in the palatal root and a discreet widening of the periodontal ligament space. The radiograph also revealed that tooth 13 had been extracted and replaced with an implant and prosthetic crown. According to the patient, tooth 13 became unbearably painful before the sinus surgery, necessitating removal. Despite the extraction, the patient continued to experience pain, requiring another CBCT.

The new CBCT revealed that the dental implant had perforated the sinus floor, causing an inflammatory process (Figure 2B). The patient was then referred to a maxillofacial surgeon for implant replacement. In a six-month later follow-up, clinical and radiographic evaluations confirmed the resolution of the issue, with no signs of inflammation or recurrence of pain.

DISCUSSION

This article presenta a case of a patient with persistent pain caused by the extrusion of filling material into the left maxillary sinus, with a large amount displaced to the interface of the ostium-ethmoid cells, distant from the related tooth. Despite undergoing multiple procedures, the patient achieved pain relief only after the source of the problem was addressed. Persistent intraoral pain following root canal therapy poses a diagnostic challenge, requiring a comprehensive assessment of the patient's chief complaint, medical history, and clinical and radiographic findings.

Endodontic literature has extensively documented the extrusion of materials, such as gutta-percha and sealers, into the periradicular tissues or the maxillary sinus (Khongkhunthian & Reichart 2001, Brooks & Kleinman 2013, Ricucci et al. 2016). Thermoplasticized gutta-percha techniques, such as Tagger’s hybrid method used in this case, have a higher incidence of material extrusion due to the increased flowability of gutta-percha when plasticized, which consequently raises the risk of extrusion (Al-Dewani et al. 2000, Schilder 2006, Swathika et al. 2024).

Overfillings are typically preceded by over-instrumentation, but radiographs or CBCT could not confirm this in the present case. In fact, there was no evidence of excessive apical root canal enlargement. It is likely that extended use of the McSpadden compactor, operating deeper than the recommended 3–5 mm from the apex, or excessive space between the gutta-percha cones contributed to the significant amount of extruded material. The pneumatization of the maxillary sinus and the palatal root apex extending into the sinus were predisposed factors to this incident. For instance, dental factors are responsible for a large number of maxillary sinusitis cases (Tataryn 2019), reinforcing the problems associated with the proximity of teeth to the sinus cavities.

Clinicians should pay attention to the proximity between the root apices of the palatal roots of the first molars and the maxillary sinus floor. A study analyzing 1,557 palatal roots (Tian et al. 2016) found that 29% were invading the sinus, 33% were in contact with the maxillary sinus floor, and 38% were distant. Besides, among patients aged 21 to 40 years (our patient had 34 years), 32% of the palatal roots were found to invade the sinus. These findings indicate that a substantial proportion of the palatal roots of the first molars are near the maxillary sinus floor.

In the case reported here, the patient’s symptoms raised concerns about a potential vertical root fracture in tooth 13, which had been treated 10 years earlier, and a missed MB2 canal in tooth 14. Both conditions are challenging to diagnose using periapical radiographs due to their two-dimensional nature, which reinforces the indication of a CBCT^14,18,23. While the missed MB2 canal was confirmed, no signs of root fractures were identified in CBCT. Studies conducted in various populations have confirmed that maxillary molars exhibit the highest prevalence of missed canals, with the MB2 canal being the most frequently missed, with percentages ranging from 65% to 93% (Karabucak et al. 2016, Costa et al. 2019, Blanco Fuentes et al. 2024).

Despite the absence of a root fracture identified by the CBCT, this does not mean that a fracture does not exist. Even CBCT can fail to detect fractures, with its accuracy in identifying these fractures varying significantly depending on the machine used, ranging from 68% to 93% (Metska et al. 2012). The negative predictive values also vary, ranging from 75% to 55% (Metska et al. 2012). However, the absence of lateral periradicular lesions and other signs or symptoms after treatments supports the conclusion that a fracture was indeed absent.

An intriguing question is how a large amount of the extruded material was found in the anterior ethmoid cells. Several mechanisms might explain this: (a) natural anatomical pathways, such as the ostiomeatal complex, connecting the maxillary and ethmoid sinuses and allowing the material to pass between them; (b) ciliary movement within the sinuses, responsible for clearing mucus, may inadvertently transport particles; (c) sinus inflammation or infection can cause mucosal swelling, altering pressure dynamics and facilitating material movement; and (d) chronic inflammation may erode the thin bony walls between the sinuses, creating a direct route for material migration. While the exact mechanism by which this occurred is speculative, it underscores the importance of early detection to prevent serious health complications (Bandyopadhyay et al. 2015, Papadopoulou et al. 2021, Incebeyaz & Oztas 2024).

Although tooth 13 was asymptomatic and showed no evidence of a vertical root fracture on CBCT, the patient chose to have it extracted and replaced with an implant before the foreign body in the sinus was removed. This led to further complications, as the implant was improperly placed into the maxillary sinus and later required removal and replacement. Prompt surgical removal of foreign bodies is generally recommended to prevent sequelae such as acute or chronic sinusitis or mucosal cyst formation ²⁵.

Traditionally, foreign bodies in the sinus are removed via open surgery, such as Caldwell-Luc sinusotomy, which allows clearance and drainage, particularly in the presence of mucosal disease (Tanasiewicz et al. 2017). However, functional endoscopic sinus surgery has gained popularity in recent years as a less invasive alternative. This approach provides excellent visibility, facilitates the removal of small foreign bodies, and reduces the risk of infraorbital nerve damage (Nakamura et al. 2004).

This case highlights the need for caution when performing endodontic treatment on posterior maxillary teeth due to their proximity to the maxillary sinus. In cases where root apices contact, invade, or are near the sinus, thermoplasticized root canal obturation techniques should be avoided because of the increased risk of complications and severe consequences. CBCT imaging significantly improves diagnostic accuracy in cases with persistent symptoms and is an important tool in treatment planning.